In an article published in the December 1956 issue of Industrial and Engineering Chemistry, Vol. 48, No. 12, Pages 2132-7, A. M. Schiller and T. J. Suen reported on a technique of introducing sodium sulfomethyl groups into polyacrylamide through reaction with formaldehyde and sodium bisulfite. Schiller and Suen taught that the sulfomethylation reaction takes place at pH levels of higher than 10 and temperatures on the order of 50.degree.-75.degree. C. This teaching has remained uncontroverted in the literature during the years intervening to the present.
Unexpectedly, as applicants have learned from co-worker Dennis P. Bakalik who used Carbon-13 Nuclear Magnetic Resonance technology, no sulfomethylation of polyacrylamide occurs under the reaction conditions of high pH and comparatively low temperature which were specified by Schiller and Suen. Instead, polyacrylamide undergoes hydrolysis in the reaction milieu; and complex equilibria species form among formaldehyde, bisulfite and the ammonia that is generated.
Accordingly, an important object of the present invention is to provide sulfomethylpolyacrylamide and a method of synthesizing the same using formaldehyde and bisulfite.
Another broad object of the invention is to provide a simple, effective and inexpensive chemical route to sulfomethylacrylamide polymers and the like.
These and other objects and features of the present invention will become apparent from the following descriptions.